A method of storage with interleaving has heretofore been known for storing confidential data.
In the method of data storage with interleave, a series of data blocks is divided into a plurality of items of element data, time-series order of the element data is shuffled, and the element data shuffled in time-series order is stored in a memory. This ensures confidentiality of the original data block.
Known for storing the data with interleave processing is a method of shuffling the time-series order of the plurality of items of element data according to a predetermined rule and storing each element data in a memory in the shuffled order, a method of calculating an address to which the element data is to be stored with use of an arithmetic operation, and a method of storing each element data to the address calculated.
A method is proposed wherein each element is stored to a corresponding address by using a table on which a random number is written as an address for every element data [JP-A No. 347076(1993)].
However, any method of the three methods stated above adopts a single data conversion rule for interleave processing, i.e., a single shuffling rule, a single arithmetic expression, or a single table. Accordingly, if the single data conversion rule is known to anyone else, the data block can be easily restored to its original by anyone else, entailing the problem of impaired reliability as to confidentiality of the data block.
An object of the present invention is to provide an interleaving device and a deinterleaving device for ensuring the high reliability as to confidentiality of the data block.